Revaporization of liquefied natural gas by means of recycling a condensing medium in heat exchange with the natural gas is disclosed in U.S. Pat. No. 3,479,832.
Recovery of power during the vaporization of liquefied natural gas by a single expansion of a condensible circulating multicomponent refrigerant is disclosed in U.S. Pat. No. 2,975,607. An improvement of this cycle is described in a paper entitled "Power Generation from Cryogenic Machinery", presented at the LNG-6 Conference held in Tokyo, Japan from Apr. 7 through 10, 1980 and authored by Shigeetsu Miyahara.
U.S. Pat. Nos. 3,293,850 and 3,992,891 disclose power recovery processes employing non-condensing gaseous heat exchange during vaporization of the liquefied natural gas.
Cascade refrigeration systems for vaporizing liquefied natural gas during which power is recovered by means of expanders are shown in U.S. Pat. Nos. 3,068,659 and 3,183,666.